The proposed research will 1) characterize the sequence of developmental changes pursued by photoreceptors in growing amphibian larvae and 2) study the development of eye rudiments explanted and maintained under tissue culture conditions. Development will be characterized by electrophysiological techniques and correlated with anatomical specialization. The molecular requirements for maturation will be assessed under the controlled environmental conditions of tissue culture. The overall objective is to identify and characterize the molecular and cellular events responsible for the development and maintenance of vertebrate photoreceptors.